The present invention relates to a paper winding control method for an automatic drafting machine.
According to a conventional automatic drafting machine as shown in FIG. 5, it has a paper take-up means 4P mounted forwardly of a platen 2P and a paper roller supporting means 6P is mounted rearwardly of the platen 2P. A paper roller is supported by the paper roll supporting means 6P, and the paper 8P is laid across the platen 2P. By reversible rotations of a drive roller 10P, the paper 8P on the platen 2P is moved across the platen 2P in a front-to-back direction of a machine frame of the drafting machine. A writing instrument 12P is driven in a direction perpendicular to the platen 2P so as to carry out a predetermined drafting operation in a predetermined drawing or drafting space on the paper 8P. During the drafting operation, the paper 8p is allowed to become slack at Ml and M2 between the platen 2 and the paper take-up means 4P and the paper supporting means 6P, respectively, so as to avoid tension in the paper 8P. After the drafting operation is completed, the drive roller 10P drives forwardly the part of the paper on which the drafting has been performed, and the take-up means 4P winds up a length of the paper corresponding to the length upon which the drafting was performed.
According to the prior art, the paper is wound onto the paper take-up means after each drafting operation even if the length of paper moved forwardly by the drive roller 10P is small. This lowers the efficiency of the automatic drafting machine. In addition, operation of the paper take-up means after each drafting operation creates noise which can be disturbing to an operator of the drafting machine.